The present invention relates to electronic musical instruments in general, and more particularly to improvements in a tone generator system for use in electronic musical instruments of the type wherein a primary or main generator which constitutes a voltage-regulated oscillator is used for the generation of frequency signals, wherein such signals are transmitted to the loudspeaker through the medium of a first 12-tone divider circuit whose outputs transmit tone signals of a first octave, and wherein the loudspeaker also receives signals from at least one second 12-tone divider circuit whose outputs transmit tone signals of a second octave. The signals of the second octave are out of tune with the signals of the first octave.
A presently known system of the just outlined character utilizes two primary generators each of which constitutes a voltage-regulated oscillator and each of which transmits high-frequency signals to a discrete 12-tone divider circuit. By dividing the high frequency signals (e.g., 2 MHz) with a divisor which is a whole multiple of one, it is possible to obtain at the outputs of the divider circuits tone signals having an average frequency of 6 kHz. Thus, and referring to the highest tone of the octave, each divider circuit has an internal dividing ratio of Each tone system rigidly follows the frequency of the corresponding primary generator.
The two primary generators are slightly out of tune to thus accomplish a certain amount of interference or beating of the tone. Such effect is especially interesting when the musical instrument is to generate tones in imitation of a piano wherein the generation of tones takes place by resorting to two or more strings which are slightly out of tune. In order to achieve such slight interference effects, the regulating voltages for the two primary generators must deviate, at least very slightly, from one another. However, even if one employs voltage-regulated oscillators which are designed to furnish high-constancy frequency signals, the difference between the frequencies of signals which are furnished by two discrete primary generators is bound to change with time. Therefore, it is necessary to resort to complex and expensive tuning systems which are intended to correct such errors, i.e., to correct deviations of the difference between the two high-frequency signals from a desired value.